Dr. Heather Mattila, Wellesley College – Promiscuous Queen Bees

In today’s Academic Minute, Dr. Heather Mattila of Wellesley College reveals how the health of a bee colony is related to the sexual behavior of the queen.

Heather Mattila is an Assistant Professor in the Department of Biological Sciences at Wellesley College. Her research focuses on the role that intracolonial genetic diversity plays in the organization of communication and division of labor in honey bee colonies. She earned her Ph.D. in Environmental Biology at the University of Guelph in Guelph, Ontario.

Honey bees queens have a behavior that is unusual for social insects. Queens of all species are highly promiscuous, meaning each queen mates with many males. This promiscuity is puzzling—why mate with so many males when it dilutes the close family ties that keep bees working hard to help their family? It turns out that colonies filled with step families are healthier and more productive than colonies of full siblings. This difference is important because it provides clues about how we can promote honey bee well being, and the need for this knowledge has never been more urgent. Up to 40% of U.S. colonies have died in the last 5 years, and while the causes of this decline remain a mystery, my research reveals how promiscuity enhances colony function.

Working with Irene Newton, a microbiologist at Indiana University, and with help from Wellesley College students, I looked for signs of health in the honey bee gut. We compared the genetic fingerprint of active gut bacteria in two groups of colonies. The first group was genetically diverse, produced by promiscuous queens that had been inseminated by 15 males each. The second group was genetically uniform—offspring from queens mated with just one male each.

What we found was remarkable: diverse colonies had a much greater variety of bacteria– more than 1,100 species, while the uniform colonies had just over 700. Furthermore, colonies with promiscuous queens had fewer pathogenic microbes and 40% more bacteria from groups that are known to benefit their hosts. Bacteria serve a critical function in colonies – they transform pollen into “bee bread,” a highly nutritious food product that can be stored long term by honey bees.

This work is our first insight into how queen promiscuity can improve the health of colonies. It gives bees broader microbial communities, which likely contribute to the health and nutrition of our most important pollinator.